1. Field of the Invention
This invention relates generally to a VTR (video tape recorder) frequency modulating circuit, and more particularly is directed to a white level clipping circuit which clips the white peak of a video signal to prevent the FM signals obtained therefrom from being over-modulated.
2. Description of the Prior Art
In a prior art clipping circuit, the anode of a diode provided for clipping is connected between the input and output terminals of the circuit, and the cathode of the diode is supplied with a constant bias voltage and also by-passed or connected to ground through a parallel circuit of a resistor and a capacitor.
When the white peak level of a video signal exceeds the sum voltage of the forward voltage across the diode and its cathode voltage, the diode becomes conductive or is ON and the white peak portion is by-passed through the diode and the parallel circuit of the resistor and capacitor. Thus, a clipped video signal is delivered to the output terminal.
In this prior art circuit, however, when the diode is ON, the impedance from its anode to the ground is high. Therefore, the white peak may not be clipped sufficiently or frequency characteristics may be imparted thereto by the provision of the capacitor.